Re: First stab at getting bar extents right. (issue 5186049)

[Keith OHara]

 <mtsolo <at> gmail.com> writes:

> However, [barlines] do not block accidentals hanging
> over, and furthermore, this extra height blocks some lyrics but not
> others.

Accidentals hanging over didn't seem to bother anybody, and we do want 
other things tied to note-columns to cross over bar-lines, such as
text markup.

The case of lyrics passing under the bar line should be very rare
<http://lists.gnu.org/archive/html/lilypond-devel/2011-02/msg00481.html>
It happens in short test files, though, and might cause confusion and
wasted time.

> The pure height of barlines should correspond to the height of
> neighboring grobs in the VerticalAlignment,

I'm assuming "pure height" means the height estimate used before 
line-breaking, and neighboring means nearest-neighbors on each side.

What is a VerticalAlignment, and which grobs does it contain?

> 1) It allows lyrics to recede all the way back to the StaffStartBar

The staff start bar doesn't seem to get a horizontal skyline.  If we 
want lyrics to get padding from the start bar, we would need to compute
a horizontal skyline for it, so that *_paper_column:minimum_distance()
finds the collision and returns the right distance to make a rod to 
enforce the padding.

> Furthermore, it seems like the horizontal skylines are outta whack,

They are drawn as if the staves, lyrics lines, etc, are all compressed
vertically, because they get used before line breaking and thus before
things get vertically stretched.